1. Field
This specification relates to a method, apparatus and program for image processing, and more particularly to a method, apparatus, and program for image processing capable of preventing, detecting and correcting image alteration.
2. Discussion of the Background
Recently, with the increase in speed and capacity of an image forming processor, digital image data is easily processed, edited, or copied. In addition, such digital image data is easily transmitted through a communication line or viewed on a network. However, with the widespread use of digital image data comes a growing threat of image alteration, such as image tampering.
One approach for detecting image alteration is to incorporate an invisible watermark into an original image and then detect its presence in a suspected image copy. For example, one background watermarking technique divides an original document image into an arbitrary number of small blocks. For each block, the background technique embeds a watermark into an LSB (least significant bit) bit-plane of the image. To detect image alteration, a suspected image is divided into the arbitrary number of small blocks, and for each of the blocks, a watermark is extracted. In this case, alteration is detected where the extracted watermark does not match with the embedded watermark.